package com.vois.jack.btmgr.devices.WL100Dev;

/**
 * Created by zrd on 2015/9/22.
 */

/** G.711 codec.
 * This class provides methods for u-law, A-law and linear PCM conversions.
 */
public class G711 {

    static final int SIGN_BIT = 0x80;    // Sign bit for a A-law byte.
    static final int QUANT_MASK = 0xf;   // Quantization field mask.
    static final int NSEGS = 8;          // Number of A-law segments.
    static final int SEG_SHIFT = 4;      // Left shift for segment number.
    static final int SEG_MASK = 0x70;    // Segment field mask.

    static final int[] seg_end = {
            0xFF, 0x1FF, 0x3FF, 0x7FF, 0xFFF, 0x1FFF, 0x3FFF, 0x7FFF
    };

    // copy from CCITT G.711 specifications

    /**
     * u- to A-law conversions
     */
    static final int[] _u2a = {

            1, 1, 2, 2, 3, 3, 4, 4,
            5, 5, 6, 6, 7, 7, 8, 8,
            9, 10, 11, 12, 13, 14, 15, 16,
            17, 18, 19, 20, 21, 22, 23, 24,
            25, 27, 29, 31, 33, 34, 35, 36,
            37, 38, 39, 40, 41, 42, 43, 44,
            46, 48, 49, 50, 51, 52, 53, 54,
            55, 56, 57, 58, 59, 60, 61, 62,
            64, 65, 66, 67, 68, 69, 70, 71,
            72, 73, 74, 75, 76, 77, 78, 79,
            81, 82, 83, 84, 85, 86, 87, 88,
            89, 90, 91, 92, 93, 94, 95, 96,
            97, 98, 99, 100, 101, 102, 103, 104,
            105, 106, 107, 108, 109, 110, 111, 112,
            113, 114, 115, 116, 117, 118, 119, 120,
            121, 122, 123, 124, 125, 126, 127, 128
    };

    /**
     * A- to u-law conversions
     */
    static final int[] _a2u = {

            1, 3, 5, 7, 9, 11, 13, 15,
            16, 17, 18, 19, 20, 21, 22, 23,
            24, 25, 26, 27, 28, 29, 30, 31,
            32, 32, 33, 33, 34, 34, 35, 35,
            36, 37, 38, 39, 40, 41, 42, 43,
            44, 45, 46, 47, 48, 48, 49, 49,
            50, 51, 52, 53, 54, 55, 56, 57,
            58, 59, 60, 61, 62, 63, 64, 64,
            65, 66, 67, 68, 69, 70, 71, 72,
            73, 74, 75, 76, 77, 78, 79, 79,
            80, 81, 82, 83, 84, 85, 86, 87,
            88, 89, 90, 91, 92, 93, 94, 95,
            96, 97, 98, 99, 100, 101, 102, 103,
            104, 105, 106, 107, 108, 109, 110, 111,
            112, 113, 114, 115, 116, 117, 118, 119,
            120, 121, 122, 123, 124, 125, 126, 127
    };


    static int search(int val, int[] table) {
        for (int i = 0; i < table.length; i++) if (val <= table[i]) return i;
        return table.length;

    }


    /**
     * Converts a 16-bit linear PCM value to 8-bit A-law.
     * <p/>
     * It accepts an 16-bit integer and encodes it as A-law data.
     * <p/>
     * Linear Input Code    Compressed Code
     * -----------------    ---------------
     * 0000000wxyza         000wxyz
     * 0000001wxyza         001wxyz
     * 000001wxyzab         010wxyz
     * 00001wxyzabc         011wxyz
     * 0001wxyzabcd         100wxyz
     * 001wxyzabcde         101wxyz
     * 01wxyzabcdef         110wxyz
     * 1wxyzabcdefg         111wxyz
     * <p/>
     * For further information see John C. Bellamy's Digital Telephony, 1982,
     * John Wiley & Sons, pps 98-111 and 472-476.
     */
    public static int linear2alaw(int pcm_val) // 2's complement (16-bit range)
    {
        int mask;
        int seg;
        //unsigned char aval;
        int aval;

        if (pcm_val >= 0) {
            mask = 0xD5; // sign (7th) bit = 1

        } else {
            mask = 0x55; // sign bit = 0
            pcm_val = -pcm_val - 8;

        }

        // Convert the scaled magnitude to segment number.
        seg = search(pcm_val, seg_end);

        // Combine the sign, segment, and quantization bits.
        if (seg >= 8) // out of range, return maximum value.
            return (0x7F ^ mask);
        else {
            aval = seg << SEG_SHIFT;
            if (seg < 2) aval |= (pcm_val >> 4) & QUANT_MASK;
            else aval |= (pcm_val >> (seg + 3)) & QUANT_MASK;
            return (aval ^ mask);

        }

    }

    /**
     * Converts an A-law value to 16-bit linear PCM
     */
    //public static int alaw2linear(unsigned char a_val)
    public static int alaw2linear(int a_val) {
        int t;
        int seg;
        a_val ^= 0x55;
        t = (a_val & QUANT_MASK) << 4;
        //seg=((unsigned)a_val&SEG_MASK)>>SEG_SHIFT;
        seg = (a_val & SEG_MASK) >> SEG_SHIFT;
        switch (seg) {
            case 0:
                t += 8;
                break;
            case 1:
                t += 0x108;
                break;
            default:
                t += 0x108;
                t <<= seg - 1;

        }
        return ((a_val & SIGN_BIT) != 0) ? t : -t;

    }


    /**
     * Bias for linear code.
     */
    public static final int BIAS = 0x84;


    /**
     * Converts a linear PCM value to u-law
     * <p/>
     * In order to simplify the encoding process, the original linear magnitude
     * is biased by adding 33 which shifts the encoding range from (0 - 8158) to
     * (33 - 8191). The result can be seen in the following encoding table:
     * <p/>
     * Biased Linear Input Code   Compressed Code
     * ------------------------   ---------------
     * 00000001wxyza              000wxyz
     * 0000001wxyzab              001wxyz
     * 000001wxyzabc              010wxyz
     * 00001wxyzabcd              011wxyz
     * 0001wxyzabcde              100wxyz
     * 001wxyzabcdef              101wxyz
     * 01wxyzabcdefg              110wxyz
     * 1wxyzabcdefgh              111wxyz
     * <p/>
     * Each biased linear code has a leading 1 which identifies the segment
     * number. The value of the segment number is equal to 7 minus the number
     * of leading 0's. The quantization interval is directly available as the
     * four bits wxyz.  The trailing bits (a - h) are ignored.
     * <p/>
     * Ordinarily the complement of the resulting code word is used for
     * transmission, and so the code word is complemented before it is returned.
     * <p/>
     * For further information see John C. Bellamy's Digital Telephony, 1982,
     * John Wiley & Sons, pps 98-111 and 472-476.
     */
    public static int linear2ulaw(int pcm_val)// 2's complement (16-bit range)
    {
        int mask;
        int seg;
        //unsigned char uval;
        int uval;

        // Get the sign and the magnitude of the value.
        if (pcm_val < 0) {
            pcm_val = BIAS - pcm_val;
            mask = 0x7F;

        } else {
            pcm_val += BIAS;
            mask = 0xFF;

        }
        // Convert the scaled magnitude to segment number.
        seg = search(pcm_val, seg_end);

        // Combine the sign, segment, quantization bits; and complement the code word.

        if (seg >= 8) return (0x7F ^ mask); // out of range, return maximum value.
        else {
            uval = (seg << 4) | ((pcm_val >> (seg + 3)) & 0xF);
            return (uval ^ mask);

        }

    }

    /**
     * ConvertS a u-law value to 16-bit linear PCM.
     * <p/>
     * First, a biased linear code is derived from the code word. An unbiased
     * output can then be obtained by subtracting 33 from the biased code.
     * <p/>
     * Note that this function expects to be passed the complement of the
     * original code word. This is in keeping with ISDN conventions.
     */
    //public static int ulaw2linear(unsigned char u_val)
    public static int ulaw2linear(int u_val) {
        int t;
        // Complement to obtain normal u-law value.
        u_val = ~u_val;
        // Extract and bias the quantization bits. Then shift up by the segment number and subtract out the bias.
        t = ((u_val & QUANT_MASK) << 3) + BIAS;
        //t<<=((unsigned)u_val&SEG_MASK)>>SEG_SHIFT;
        t <<= (u_val & SEG_MASK) >> SEG_SHIFT;

        return ((u_val & SIGN_BIT) != 0) ? (BIAS - t) : (t - BIAS);

    }


    /**
     * A-law to u-law conversion.
     */
    //public static int alaw2ulaw(unsigned char aval)
    public static int alaw2ulaw(int aval) {
        aval &= 0xff;
        return ((aval & 0x80) != 0) ? (0xFF ^ _a2u[aval ^ 0xD5]) : (0x7F ^ _a2u[aval ^ 0x55]);

    }


    /**
     * u-law to A-law conversion.
     */
    //public static int ulaw2alaw(unsigned char uval)
    public static int ulaw2alaw(int uval) {
        uval &= 0xff;
        return ((uval & 0x80) != 0) ? (0xD5 ^ (_u2a[0xFF ^ uval] - 1)) : (0x55 ^ (_u2a[0x7F ^ uval] - 1));

    }
}

